linux-kernel - Re: [PATCH v7 4/7] KVM: VMX: Load Guest CET via VMCS when CET is enabled in Guest

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Message-ID: <CALMp9eS+_riWYK=Zvk330YST4G_q_GfN2LfGXWz85aVnyXmsOg@mail.gmail.com>
Date:   Wed, 9 Oct 2019 16:08:50 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Yang Weijiang <weijiang.yang@...el.com>
Cc:     kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH v7 4/7] KVM: VMX: Load Guest CET via VMCS when CET is
 enabled in Guest

On Tue, Oct 8, 2019 at 11:41 PM Yang Weijiang <weijiang.yang@...el.com> wrote:
>
> On Wed, Oct 02, 2019 at 11:54:26AM -0700, Jim Mattson wrote:
> > On Thu, Sep 26, 2019 at 7:17 PM Yang Weijiang <weijiang.yang@...el.com> wrote:
> > > +       if (cet_on)
> > > +               vmcs_set_bits(VM_ENTRY_CONTROLS,
> > > +                             VM_ENTRY_LOAD_GUEST_CET_STATE);
> >
> > Have we ensured that this VM-entry control is supported on the platform?
> >
> If all the checks pass, is it enought to ensure the control bit supported?

I don't think so. The only way to check to see if a VM-entry control
is supported is to check the relevant VMX capability MSR.

BTW, what about the corresponding VM-exit control?